At first, you’re going to think something is wrong. Why wouldn’t you? Mom’s never tried to get a hold of you while you’re in class.

First off, don’t worry. Everything is fine. In fact, you’ll find out things are more than fine. But you’re not going to believe what she’s going to tell you when you call her back. You’re not going to see this one coming.

When you call her back during a break between classes, everything is about to change. Very quickly.

So before you do call her back, and before everything happens, let me just say one thing that I want you to keep with you: Always play football with the hunger you’ve had. Keep your drive to improve. To do more. To be the best.

Remember that, will you? For everything that’s about to happen, never forget that hunger.

“The coach of Groningen’s first team called earlier,” Mom will tell you, once you finally speak. “He wants you to travel with them this weekend for the match.”

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I know, right? Incredible.

Why do I bring this up? Well, I’ve been thinking about that moment a lot lately. The moment when things really started. Another season has finished — your 17th, with another one coming this week. You’re 33, and you’re only playing on a one-year contract, so after that, who knows?

And maybe when the end of your career becomes more and more of a reality … you start thinking about the beginning. When it stopped being just a game.

That happened when you arrived to Groningen. And Groningen will be an opportunity that will take you to PSV, and then PSV will take you to Chelsea. At 20 years old, you’ll be in the Premier League.

And your boss? His name is José Mourinho. I should prepare you. Because he will expect a lot of you … and of everyone. Right away, you’ll feel the difference in playing for a Premier League club. You’ll need to be tougher, stronger, faster.

Maybe when the end of your career becomes more and more of a reality … you start thinking about the beginning.

You’ll have to prove yourself all over again once you get there. And prove yourself to José every single week to stay in the lineup. Look, a lot has been said about José. He’s a strong personality, he’s demanding. But ever since you started playing, you’ve been just as demanding of yourself. In a way, it’ll almost seem like a perfect match. He wants to see your very best, each and every day on the pitch. And all you’ll want to give is your best. Whether in training, or in a match.

Or working your way back from an injury.

Yes, this is going to be the first time you’re challenged in that way, too. It’s not how you wanted to start off in England … with a broken bone in your foot in a preseason match. You’ll be sidelined for more than two months. But that will only provide more motivation to prove yourself. To prove yourself to José. To your teammates. To Stamford Bridge and the fans.

You’ll want to show everyone what you can do.

And you will, with a 72nd-minute goal in your very first start at Stamford Bridge in November 2004.

It’ll be right in front of the box, off your left foot.

(And by the way, your left foot? Specifically, coming in from the right wing and shooting with your left? Work on this. Practice this. It’ll come in handy more times than you can count. Trust me on this one.)

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It’ll only be two years, but Chelsea will be an important step for you. For your manager, for dealing with injuries — but, also, that team will be something special. I give credit to José on this, he knows how to create and build a team. And this team? Well, it was a good one.

Not just because you had players like Lampard and Drogba and Čech and Terry on the pitch.

But because you had players like Lampard and Drogba and Čech and Terry off the pitch as well.

Everyone on that team was thinking about each other. Everyone was thinking about the club. The atmosphere during that time … it was amazing. A lot of the guys who have been at the club for a while will look out for you, but there will be no one more important — not only for you, but for everyone — than John Terry.

What can a Dutch winger learn from an English center back?

Everything.

The most important thing though, is what it takes to be a captain and a leader at a club. He’ll be someone you can talk to, whether about football or anything else. He’ll be someone who gives advice, who encourages you. Learn as much from him as you can. How he gives everything for the club. How he gives everything for the team — from the first to the last minute. Out there, he’s taking care of every team member. And he does the same off the pitch as well.

I’m not sure you’ll know it then, just how much John influenced you. So really take in those moments with him. You won’t play with anyone quite like him again.

Or have an experience quite like you had at Chelsea. There were titles and cups in Holland, but at Chelsea, you’ll all be part of history. The first league title in 50 years. It’s not going to feel complete at the time because you’ll be injured. But enjoy that moment more than I did then. Appreciate it properly — because you were a part of that team, you were important and you did do your job.

And then help the team win another title the year after.

And then?

There will be the next step….

Real Madrid.

In England, you’ll see from your very first match: The fans are living and breathing football. But in Spain, it’s just … different. They don’t breathe and live football, it’s just … life.

But then, after two years, you’re going to find out that football is also … business.

And you’re not going to be happy about it.

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See, up until this point, everything has made sense. From being a boy playing at school and on little pitches, to Groningen, to PSV, to Chelsea, to Real Madrid…. To league titles and cups and Champions League semi-finals.

All of it, it was always about moving forward, about improving, about finding a new challenge.

It was always about taking the next step. That’s how you wanted to play your game.

But Bayern? You’ll see it as a step backward. Of course, they have the league titles and the cup titles, but for you, right now, it’s about winning a Champions League, for which Bayern haven’t been favorites. At Chelsea and at Real Madrid, you didn’t get there, either.

And I know what you’ll be be thinking when you hear about this move: Now I definitely won’t get there.

Real Madrid was the biggest club in the world at the time. And you’ll feel that, with them, you’re at the top of the mountain, and anything else is a step down.

But here’s something I want you to know: You couldn’t be more wrong about anything in your life.

Because coming to Bayern will be the best decision you will ever make.

You’ll be a part of something more at Bayern. Because success won’t just be on the pitch, but on all levels. You’ll see. Financially. Globally. In Germany and across Europe — that badge and those colors will mean something.

You’ll be a part of something more at Bayern.

No one will expect you to do it, but the team will make it to the finals of the Champions League in your first year.

You’ll get knocked out early in 2011, but by the next year … it will be Bayern’s moment. The 2012 Champions League final, in front of your home crowd at the Allianz Arena. Against your former club, Chelsea.

It couldn’t have been written any better.

Except … and I don’t know how to tell you this, but … it turns into a nightmare.

A lot will be said about that final, what you could’ve done … what you didn’t do. But there’s something else that people won’t write about or see. And that was the first day back at training, a few weeks later. To be honest, you were ready to get back to training the day after the final. But maybe that time is something you all needed. Because when you do go back there’s … a feeling.

You’ve had plenty first days back in your career. And they all go the same way. Everyone’s lightly getting back into the rhythm, OK, here we go…

But not this time. This time it was actually more than just a feeling, it was a spirit. Everybody wanted something. One thing, really.

Revenge.

And every match, whether in the Bundesliga, or a cup game or a Champions League qualifier is going to be played to right the wrong of that final. Every win, every goal is going to be about getting back there again.

And remember that left-footed shot I told you about? Think about it.

Think about it when you do reach the Champions League final that year. Think about it when, in the second half, shortly after Bayern takes the lead, Borussia Dortmund ties the game 1-1.

Think about it in the 89th minute, with hardly any time remaining.

Cut in from the right, control with your left.

And let it go.

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The eight years you have at Bayern Munich will be the proudest of your career. Three Champions League semifinals. Three finals. One Champions League trophy. Six Bundesliga titles. Four cup trophies.

But aside from the trophies, the titles, I don’t think I can prepare you for how much this club will come to mean to you. Maybe even more so because you didn’t expect it to.

So what else can I say?

Well, for one thing, there will be a pretty strange exit from the Champions League in 2017. I’ll just leave it at that.

But what I really want you to know is that even at 33, that hunger you have now is still here. That drive to keep getting better hasn’t left yet. Looking back, I think that’s what gets us here more than anything — that desire, no matter what you’ve already done, to keep going back out, to keep getting more from the pitch.

So I’m not sure when that moment will come — when that hunger will leave. I don’t know whether it’ll be next year or the year after, but when it does come, I believe we’ll know that it’ll be time to think about something else.

Maybe stepping back, maybe quitting … maybe making one little last move, to some other adventure?